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FREE CODE DOWNLOADS: IRC Appendix AS & Appendix AR with Commentary

30 May 2015 11:30 PM | Anonymous member (Administrator)

Appendix AS – Strawbale Construction with Commentary

Appendix AR - Light Straw-Clay Construction with Commentary

from the 2021 International Residential Code (IRC)

Free Download  (please download only the Appendix or Appendices you need)

Appendix AS with Commentary
To receive your free download:
  1. Visit the Download page
  2. Click Add to Bag button
  3. Shopping Bag will appear in lower right corner of your browser
  4. Click Open Bag link
  5. Complete checkout process

Appendix AS and Appendix AR as downloaded from this page are from the 2021 International Residential Code and Commentary as published by the International Code Council (ICC). These downloads are made available by agreement between CASBA and the ICC.

The complete  IRC and Commentary is available for purchase from the ICC here: 

The 2021 IRC without  commentary is also available as read-only (not downloadable) for free on ICC’s website at

Appendix AS and Appendix AR sometimes reference sections of the IRC, so access to the complete IRC is important for full understanding and full use. The IRC applies to one and two-family dwellings, their accessory structures and townhouses.

The IRC is a model code with no legal standing of its own, but it is the basis for the residential code in virtually every state and local jurisdiction in the United States. However, many jurisdictions have not yet adopted the 2021 IRC, and some may not adopt Appendix AS or Appendix AR. Jurisdictions that do adopt Appendix AS and Appendix AR may also amend them. Consult your local building department to understand which edition of the IRC is the basis for its current building code and whether Appendix AS and Appendix AR are included.

Project applicants who wish to use Appendix AS or Appendix AR for a project where the state or local jurisdiction has not adopted the 2021 IRC or the Appendix, can propose their use on a project basis with the local building official.

The Commentary describes intent, and gives compliance examples for the Appendix code requirements. This is especially helpful for design professionals, builders, building owners, and code officials with little or no experience with strawbale or light straw-clay construction.

Appendix AS and California

Appendix AS from the 2021 IRC is included with minor amendment in the 2022 California Residential Code (CRC) and was adopted by the Department of Housing and Community Development (HCD) for mandatory statewide use. The 2022 CRC took effect January 1, 2023 for permit applications dated Jan. 1, 2023 through Dec 31, 2025. If a local building department or official claims their jurisdiction did not adopt Appendix AS or otherwise refuse to use Appendix AS, please contact Martin Hammer (see below).

Appendix AR with Commentary
To receive your free download:
  1. Visit the Download page
  2. Click Add to Bag button
  3. Shopping Bag will appear in lower right corner of your browser
  4. Click Open Bag link
  5. Complete checkout process

Appendix AR and California

Appendix AR from the 2021 IRC is included in the 2022 California Residential Code, for voluntary use by local jurisdictions. Unlike Appendix AS, it was not adopted by a state agency for mandatory statewide use, but it can be proposed for use on a project basis.

Other Editions of Appendix AR or AS(2015, 2018 and information re: 2024) can be obtained through Martin Hammer (see below). Past editions could be in force for current or past projects depending on the State or local jurisdiction and the project application date. The 2024 IRC and appendices have been finalized through ICC’s code development process and will be published sometime in 2023. They will go through State and local adoption in subsequent years.

Questions or Comments regarding IRC Appendix AS and Appendix AR can be directed to their lead author, Martin Hammer, at .

Appendix AU – Cob Construction (Monolithic Adobe)

Appendix AU is available for free download through the Cob Research Institute (CRI) at

Consider a Donation to CASBA

CASBA is happy to offer IRC Appendices for free download, but also encourages donations that help fund our ongoing agreement with ICC, and help allow CASBA members to periodically revise the appendices and advocate for other sustainable advances in the building codes. Please donate here

CASBA is fiscally sponsored by the Tides Center, a 501(c) (3) non-profit organization.

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